Drill steel guiding and centralizing mechanism

ABSTRACT

A drill steel guiding and centralizing mechanism comprising a body (14) and a first and second jaw (1 and 6) connected to other ends of two-armed angled levers (2,3 and 7,8). The angled levers are turnably connected to the body (14) by joints (4 and 9) at the corner points between the arms (2 and 3; 7 and 8). The ends of the free arms (3 and 8) of the angled levers are connected to each other by a connecting road (11), the ends of which are connected to the ends of the arms (3 and 8) by swivel joints (12 and 13). The second angled lever (2,3) has an extension (16) which is affected by the power mechanism (15) substantially parallelly to the connecting rod (11). Thereby the jaws (1 and 6) can be opened and closed by the power mechanism (15) exactly centralized in relation to the drill steel.

This invention relates to a drill steel guiding and centralizingmechanism which mechanism is of the type described in claim 1.

Swedish publication No. 353 762 discloses a drill steel guidingmechanism in which the guiding jaws are turnable around a common axis,and can be opened and closed by means of arms on both sides of the axis,which arms are provided with cams and wedge surfaces to take hold of thejaws. A disadvantage of this mechanism is that dirt and stone dust whichgoes between the wedge surfaces and between the cams and their countersurfaces cause wear and unaccurate centralizing. Because the jaws areclosed with the aid of sharp wedge surfaces, a considerable part of thecylinder power is lost through friction, and part of the power affectsin a wrong direction.

Swedish Pat. No. 215 154 discloses a drill steel guiding andcentralizing mechanism in which device the jaws are movable by means oftwo cylinders operating opposite to each other. However, the cylindersmay have different speeds of movement, e.g. due to different friction,whereby one of the jaws reaches the drill steel earlier and pushes thesteel aside until the other jaw is met. Thus the centralizing isunaccurate. The mechanism is neither suitable for drill cuttings suctionpipes of a large diameter. If the jaw travel increases, the centralizingaccuracy will further decrease. These disadvantages of the known guidingand centralizing mechanisms cause among others the following additionaldisadvantages: Drilling speed decreases, the drilling direction becomesless accurate, the drilling machine is subjected to extra torsionalloads and the life of the shank adapter is shorter. If an automaticdrill steel handling mechanism is used, accurate centralizing of thedrill steel is absolutely necessary. This requirement is notsufficiently fulfilled by the known drill steel guiding and centralizingmechanisms.

The object of this invention is to develop an improved drill steelguiding and centralizing mechanism which eliminates the disadvantages ofthe know guiding and centralizing mechanisms and makes the centralizingof the steel reliable and accurate.

This object is reached through the characteristics of the inventiondefined in claim 1.

My invention is further described in more detail with reference to thefollowing Figure descriptions:

FIG. 1 illustrates a sideview of a drill steel guiding and centralizingmechanism with a power mechanism coupled with one of its lever arms; and

FIGS. 2, 3, 4, 5, 6 and 7 illustrate side views of the mechanism asillustrated in FIG. 1 only with the power mechanism coupled in differentways with the various levers which form a part of the mechanism.

Numbers 1 and 6 in the drawing refer to the jaws for guiding andcentralizing the drill steel; the jaws are shown in the closed position.Jaw 1 is connected to the first lever arm of the first angled lever 5.The angled lever 5 further comprises another lever arm 3 and anextension 16 therefor. The angled lever 5 is mounted on the body 14 by aswivel joint 4 which is between the lever arms 2 and 3.

The other jaw 6 is connected to the other angled lever 10 which alsocomprises two lever arms 7 and 8. Between these there is a swivel joint9 by means of which the angled lever 10 is turnably mounted on the body14. The radius of the holes of the jaws at the drill steel centre linecan be made suitable e.g. for the fastening of the extension rods to theconnecting socket. In this case the jaws are not closed against eachother.

The lever arms 3 and 8 of the angled levers 5 and 10 are connected by afirm connecting rod 11 which is fastened to the arms 3 and 8 by swiveljoints 12 and 13. The swivel joints 12 and 13 and the joints 4 and 9 areplaced preferably in the corners of a parallelogram. The extension 16 ofthe lever arm 3 is connected to a piston cylinder device 15, the otherend of which is in the body 14. The piston cylinder device can becoupled to affect any of the lever arms 2, 3, 7, 8 or the connecting rod11 between the second lever arm 3 and the fourth lever arm 8. When thepiston cylinder device 15 is lengthened, the jaws 1, 6 opensymmetrically in relation to the drill rod centre line. If the length Aof both lever arms 2 and 7 is equal, the travel of both jaws is thesame. Thus the centralizing accuracy of the jaws remains good even ifthe jaws would not touch each other in the closed position, e.g. whentaking hold of the connecting socket for extension rods by the jaws.Because the jaws open symmetrically, they are suitable also for mountingdrill cuttings suction pipes. By adjusting mutually the dimensions A, Band C, the jaw travel and pressing power can be changed in relation tothe stroke and the power of the piston cylinder device 15. E.g. when therelation A/B grows, the jaw travel increases even when the stroke of thecylinder remains unchanged. Thus the lever dimensions are defined by theavailable force F and the desired travel of the jaws 1,6.

I claim:
 1. A drill steel guiding and centralizing mechanism comprisinga body (14), a first jaw (1), a first lever arm (2) directly connectedby said first jaw, a second lever arm (3) directly connected to thefirst lever arm away from the connection of the first jaw with the firstlever, and an extension (16) for the second lever arm, a first swiveljoint (4) connected between the first and the second lever arms and thebody (14), around which joint the first angled lever (5) formed by thefirst and the second lever arms turns, and another jaw (6), cooperatingwith the first jaw in order to open and close the jaws, a third leverarm (7) directly connected to the second jaw, and a fourth lever arm (8)directly connected to the third lever arm away from the connection ofthe second jaw with the third lever arm, the body (14) between the thirdand the fourth lever arms, on which second joint (9) the angled lever(10) formed by the third and the fourth lever arms is swiveling, wherebythe second lever arm (3) and the fourth lever arm (8) are on the sameside in relation to the first and the second joints, and a powermechanism (15) to move the arms, the center of the jaws (1, 6) beingpositioned on a line connecting the joints (4, 9) when in a closedposition of the jaws and that the jaws are movable away from and towardsthe line when the jaws are opened and closed, the improvement being thatthe second and fourth lever arms are connected through a firm connectingrod (11) that is connected to the second lever arm (3) by a third joint(12) and to the fourth lever arm (3) by a fourth joint (13) and that thepower mechanism (15) to drive the arms being coupled to affect only oneof the lever arms (2, 3, 7 or 8) or its extension, or the connecting rod(11) between the second (3) and fourth (8) lever arms, and the first(4), the second (9), the third (12) and the fourth (13) joints beingcorner points of a parallelogram.
 2. A mechanism according to claim 1,the improvement being that the first (2) and the third (7) lever armsare equally long.
 3. A mechanism according to claim 2, the improvementbeing that the power mechanism (15) driving the levers is directlyconnected to the extension (16) of the second (3) or fourth (8) leverarm.